Semiconductor device and method of manufacturing the same

ABSTRACT

A semiconductor device including, in cross section, a semiconductor substrate; a gate insulating film on the semiconductor substrate; a gate electrode on the gate insulating film, the gate electrode including a metal, a side wall insulating film at opposite sides of the gate electrode, the side wall insulating film contacting the substrate; a stress applying film at the opposite sides of the gate electrode and over at least a portion of the semiconductor substrate, at least portion of the side wall insulating film being between the gate insulating film and the stress applying film and in contact with both of them; source/drain regions in the semiconductor substrate at the opposite sides of the gate electrode, and silicide regions at surfaces of the source/drain regions at the opposite sides of the gate electrode, the silicide regions being between the source/drain regions and the stress applying layer and in contact with the stress applying layer.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.14/669,803 filed Mar. 26, 2015 which is a continuation of U.S. patentapplication Ser. No. 12/530,797 filed Sep. 11, 2009, now U.S. Pat. No.9,070,783 issued Jun. 30, 2015 which is the Section 371 National Stageof PCT/JP2008/053424 filed Feb. 27, 2008 the entireties of which areincorporated herein by reference to the extent permitted by law. Thepresent application claims the benefit of priority to Japanese PatentApplication Nos. JP 2007-072968 filed on Mar. 20, 2007 and JP2008-018513 filed Jan. 30, 2008 in the Japan Patent Office, theentireties of which are incorporated by reference herein to the extentpermitted by law.

TECHNICAL FIELD

The present invention relates to a semiconductor device with stressapplied to a transistor channel and a method of manufacturing the same.

BACKGROUND ART

These years, semiconductor integrated circuits have achieved a higherlevel of integration, higher speed, and lower power consumption, andthere has been an increasing demand for improving the quality oftransistors. There are various methods of enhancing the ability of atransistor. Especially, a method of raising the mobility of carriers byapplying a proper stress on a semiconductor device, with a stressed thinfilm layered on the surface thereof, is in widespread use because it isfree from side effects, such as a capacity increase, in a transistorhaving a gate length of 100 nm or less (for example, refer toJP-A-2002-198368, JP-A-2005-57301, JP-A-2006-165335, andJP-A-2006-269768).

The conventional method of manufacturing a transistor using a stressapplying film will be described with reference to the manufacturingprocesses in FIGS. 26 to 28 .

As illustrated in FIG. 26 (1), an element isolating region 114 of theSTI (Shallow Trench Isolation) structure is formed on a siliconsubstrate 111.

Next, as illustrated in FIG. 26 (2), a silicon oxide film (notillustrated) is formed through surface oxidation as a protective filmfor channeling prevention when the impurities are ion-implanted in thesilicon substrate 111. Then, the impurities are ion-implantedrespectively in the n-type transistor area and the p-type transistorarea, thus forming a p-type well region 115 and an n-type well region116.

Then, the protective silicon oxide film is removed and a gate oxide film141 is newly formed in a thickness of about 1 to 3 nm as illustrated inFIG. 26 (3).

Next, as illustrated in FIG. 26 (4), after a polysilicon film is formedon the gate oxide film 141 with a film thickness of about 100 to 150 nm,a photolithography technique and a dry etching technique are used toform gate electrodes 143 and 163 with a polysilicon film.

Next, as illustrated in FIG. 27 (5), through impurity implantation,n-type extension regions 131 and 132 are formed in the n-type transistorregion through implantation of n-type impurities, such as As ions, Pions, and the like, while p-type extension regions 151 and 152 areformed in the p-type transistor region through implantation of p-typeimpurities, such as B ions and so on.

Next, as illustrated in FIG. 27 (6), after gate side wall insulatingfilms 133 and 153, including a silicon nitride film or oxide film with athickness of about 20 nm to 50 nm, are formed according to the CVDmethod and the dry etching method, impurity ions are implanted, to formsource/drain regions 135 and 136 in the n-type transistor region andsource/drain regions 155 and 156 in the p-type transistor region. Then,by applying heat at a temperature of about 1050° C. instantaneously, theimpurities are activated.

Next, as illustrated in FIG. 27 (7), silicide electrodes 137, 138, 157,158, 139, and 159 with thicknesses of about 20 nm to 50 nm are formed onthe source/drain regions 135, 136, 155, and 156 and the gate electrodes143 and 163 using cobalt (Co), nickel (Ni) or the like, according tosalicide process technology, hence to reduce resistance there.

Next, as illustrated in FIG. 28 (8), a compressive liner film 122 formedof a silicon nitride film having a compressive stress of about 1 GPa to3 GPa, is formed on p-type transistor 103 in a thickness of about 20 nmto 60 nm according to the CVD method, optical lithographymethod, and dryetching method.

Further, as illustrated in FIG. 28 (9), a tensile liner film 121 formedof a silicon nitride film having a tensile stress of about 1 GPa to 2GPa, is formed on n-type transistor 102 through the CVD method, opticallithography method, and dry etching method. Due to the effect of thisliner film, a compressive stress is applied to a channel of the p-typetransistor in the direction of the channel to improve the mobility ofholes and a tensile stress is applied to a channel of the n-typetransistor to improve the mobility of electrons.

Next, as illustrated in FIG. 28 (10), an interlayer insulating film 171formed of silicon oxide (SiO₂) or the like is formed through the CVDmethod. Further, after a contact hole is bored according to the dryetching technique, metal of tungsten (W) or the like is embedded to formcontact electrodes 144, 145, 164, and 165 which connect to thesource/drain regions 135, 136, 155, and 156, thereby a transistor 101 iscompleted.

In the conventional transistor structure, by forming a stressed thinfilm on the completed transistor device, it is possible to apply astress on the device and improve the mobility of the transistorcomparatively easily; however, there is a problem in that only a smallstress is imposed on the channel of the transistor, compared with thestress of the thin film, because of the repulsive force from the gateelectrodes. In order to impose a large stress there, it is necessary toget the film thicker or to get the internal stress itself of the filmlarger. When the film gets thicker, however, there are some problems,namely, it comes into contact with the adjacent transistor portion,which decreases the effect of stress, and boring a contact hole becomesdifficult because a portion of the silicon nitride film becomes thicker.Further, when the internal stress of the film gets larger, there is aproblem in that defects of the film, such as cracks, occur.

The problem to be solved is that, in the structure of forming a thinfilm having a stress on a transistor device, only a small stress can beapplied on the channel of the transistor, compared with the stress ofthe thin film, because of the repulsive force from the gate electrodes.

The present invention aims to enhance a current increasing effect byincreasing a stress to be applied on the transistor channel.

DISCLOSURE OF THE INVENTION

The present invention according to claim 1 is characterized bycomprising: a side wall insulating film which is formed on asemiconductor substrate with a trench formed by removing a dummy gate; agate electrode which is formed on the semiconductor substrate within thetrench through a gate insulating film; a stress applying film which isformed along the side wall insulating film over the semiconductorsubstrate; and source/drain regions which are formed in thesemiconductor substrate on the both sides of the gate electrode, in thatthe stress applying film is formed before the trench is formed.

In the invention according to claim 1, since the stress applying film isformed before the trench is formed, the dummy gate is removed in such astate that a stress is applied on the semiconductor substrate owing tothe stress applying film. Therefore, the stress which has been appliedon the dummy gate comes to be applied on the semiconductor substrate ofthe region where the dummy gate is removed, namely, a transistor channelregion, thereby a stress to be applied on the channel region increases.

The invention according to claim 5 is characterized by comprising: ann-type transistor, in an n-type transistor forming region of thesemiconductor substrate, having a side wall insulating film which isformed on the semiconductor substrate with a first trench formed byremoving a first dummy gate, a gate electrode which is formed on thesemiconductor substrate within the second trench through a gateinsulating film, a first stress applying film having a tensile stresswhich is formed along the side wall insulating film over thesemiconductor substrate, and source/drain regions which are formed inthe semiconductor substrate on the both sides of the gate electrode; anda p-type transistor, in a p-type transistor forming region of thesemiconductor substrate, having a side wall insulating film which isformed on the semiconductor substrate with the second trench formed byremoving a second dummy gate, a gate electrode which is formed on thesemiconductor substrate within the second trench through the gateinsulating film, a second stress applying film having a compressivestress which is formed along the side wall insulating film over thesemiconductor substrate, and source/drain regions which are formed inthe semiconductor substrate on the both sides of the gate electrode, inthat the first stress applying film is formed before the first trench isformed, and the second stress applying film is formed before the secondtrench is formed.

In the invention according to claim 5, since the first stress applyingfilm is formed before the first trench is formed and the second stressapplying film is formed before the second trench is formed, the dummygates are removed in such a state that stresses are applied on thesemiconductor substrate owing to the respective stress applying films.Therefore, the stresses which have been applied on the dummy comes to beapplied on the semiconductor substrate of the regions where the dummygates are removed, namely, transistor channel regions, therebyincreasing stresses to be applied on the channel regions.

The invention according to one embodiment is characterized bycomprising: a process of forming a dummy gate on semiconductorsubstrate, thereafter forming a side wall insulating film on each sidewall of the dummy gate, and forming source/drain regions in thesemiconductor substrate on the both sides of the dummy gate; a processof forming a stress applying film along the side wall insulating filmover the semiconductor substrate; a process of forming a trench byremoving the dummy gate; and a process of forming a gate electrode onthe semiconductor substrate within the trench through a gate insulatingfilm.

In the invention according to this embodiment, since the stress applyingfilm is formed before the trench is formed, the dummy gate is removed insuch a state that the stress is applied on the semiconductor substrateowing to the stress applying film. Therefore, the stress which has beenapplied on the dummy gate comes to be applied on the semiconductorsubstrate of the region where the dummy gate is removed, namely, atransistor channel region, thereby a stress to be applied on the channelregion increases.

The invention according to another embodiment is characterized bycomprising: a process of forming each dummy gate in an n-type transistorforming region and a p-type transistor forming region on semiconductorsubstrate, thereafter forming a side wall insulating film on the sidewalls of the respective dummy gates, and forming source/drain regionsrespectively in the semiconductor substrate on the both sides of therespective dummy gates; a process of forming a first stress applyingfilm along the side wall insulating film over the semiconductorsubstrate in the p-type transistor forming region; a process of forminga second stress applying film along the side wall insulating film overthe semiconductor substrate in the p-type transistor forming region; aprocess of forming trenches by removing the respective dummy gates; anda process of forming gate electrodes on the semiconductor substratewithin the respective trenches through a gate insulating film.

In the invention according to another embodiment, since the first stressapplying film is formed before the first trench is formed and the secondstress applying film is formed before the second trench is formed, thedummy gates are removed in such a state that stresses are applied on thesemiconductor substrate owing to the respective stress applying films.Therefore, the stresses which have been applied on the dummy gates comesto be applied on the semiconductor substrate of the regions where thedummy gates are removed, namely, transistor channel regions, therebyincreasing stresses to be applied on the transistor channel regions.

According to the invention, since the stress applied on the channelregion of the transistor increases, mobility can be increased extremely,thereby improving the response performance of a transistoradvantageously.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional structural view showing anembodiment (first embodiment) of a semiconductor device according to theinvention.

FIG. 2 is a cross sectional view of a manufacturing process showing theembodiment (first embodiment) of a method of manufacturing thesemiconductor device according to the invention.

FIG. 3 is a cross sectional view of a manufacturing process showing theembodiment (first embodiment) of the method of manufacturing thesemiconductor device according to the invention.

FIG. 4 is a cross sectional view of a manufacturing process showing theembodiment (first embodiment) of the method of manufacturing thesemiconductor device according to the invention.

FIG. 5 is a cross sectional view of a manufacturing process showing theembodiment (first embodiment) of the method of manufacturing thesemiconductor device according to the invention.

FIG. 6 is a cross sectional view of a manufacturing process showing theembodiment (first embodiment) of the method of manufacturing thesemiconductor device according to the invention.

FIG. 7 is a cross sectional view of a manufacturing process showing theembodiment (first embodiment) of the method of manufacturing thesemiconductor device according to the invention.

FIG. 8 is a view for use in describing effects of a stress increase inthe n-type transistor according to the first embodiment.

FIG. 9 is a view for use in describing effects of a stress increase inthe p-type transistor according to the first embodiment.

FIG. 10 is a view for use in describing effects of mobility enhancementin the n-type and p-type transistors according to the first embodiment.

FIG. 11 is a schematic cross sectional structural view showing anotherembodiment (second embodiment) of a semiconductor device according tothe invention.

FIG. 12 is a cross sectional view of a manufacturing process showing theembodiment (second embodiment) of a method of manufacturing thesemiconductor device according to the invention.

FIG. 13 is a cross sectional view of a manufacturing process showing theembodiment (second embodiment) of the method of manufacturing thesemiconductor device according to the invention.

FIG. 14 is a view for use in describing effects of a stress increase inthe n-type transistor according to the second embodiment.

FIG. 15 is a view for use in describing effects of a stress increase inthe p-type transistor according to the second embodiment.

FIG. 16 is a view for use in describing effects of mobility enhancementin the n-type and p-type transistors according to the second embodiment.

FIG. 17 is a schematic cross sectional structural view showing anotherembodiment (third embodiment) of a semiconductor device according to theinvention.

FIG. 18 is a schematic cross sectional structural view showing anotherembodiment (fourth embodiment) of a semiconductor device according tothe invention.

FIG. 19 is a view for use in describing effects of a stress increase inthe p-type transistor according to the third and the fourth embodiments.

FIG. 20 is a view for use in describing effects of mobility enhancementin the p-type transistor according to the third and the fourthembodiments.

FIG. 21 is a schematic cross sectional structural view showing anotherembodiment (fifth embodiment) of a semiconductor device according to theinvention.

FIG. 22 is a schematic cross sectional structural view showing anotherembodiment (sixth embodiment) of a semiconductor device according to theinvention.

FIG. 23 is a view for use in describing effects of a stress increase inthe p-type transistor according to the fifth and the sixth embodiments.

FIG. 24 is a view for use in describing effects of mobility enhancementin the p-type transistor according to the fifth and sixth embodiments.

FIG. 25 is a schematic cross sectional structural view showing anotherembodiment (seventh embodiment) of a semiconductor device according tothe invention.

FIG. 26 is a cross sectional view of a manufacturing process showing oneexample of a method of manufacturing a semiconductor device according tothe conventional technique.

FIG. 27 is a cross sectional view of a manufacturing process showing theexample of the method of manufacturing a semiconductor device accordingto the conventional technique.

FIG. 28 is a cross sectional view of a manufacturing process showing theexample of the method of manufacturing a semiconductor device accordingto the conventional technique.

BEST MODE FOR CARRYING OUT THE INVENTION

One embodiment (first embodiment) of a semiconductor device according tothe invention will be described with reference to the schematic crosssectional structural view in FIG. 1 .

As illustrated in FIG. 1 , element isolating regions 14 which separatean n-type transistor forming region 12 and a p-type transistor formingregion 13 electrically, are formed on a semiconductor substrate 11. Forexample, silicon substrate is used for the semiconductor substrate 11and the element isolating region 14 is formed, for example, in the STI(Shallow Trench Isolation) structure including, for example, an oxidefilm.

A p-type well region 15 with p-type impurities induced, is formed in thesemiconductor substrate 11 of the n-type transistor forming region 12,and an n-type well region 16 with n-type impurities induced, is formedin the semiconductor substrate 11 of the p-type transistor formingregion 13.

On the semiconductor substrate 11, a side wall insulating film 33 havinga first trench 39 which is formed by removing the first dummy gate (notillustrated), is formed in the n-type transistor forming region 12 and aside wall insulating film 53 having a second trench 59 which is formedby removing the second dummy gate (not illustrated), is formed in thep-type transistor forming region 13. The side wall insulating films 33and 53 are formed, for example, in thicknesses of about 20 nm to 50 nm.

A gate electrode 43 is formed within the first trench 39 through thegate insulating film 41 on the semiconductor substrate 11 and a gateelectrode 63 is formed inside the second trench 59 through the gateinsulating film 41 on the semiconductor substrate 11.

The gate insulating film 41 is formed, for example, of a hafnium oxide(HfO₂) film, an insulating film of high dielectric constant (High-k),with a thickness of about 2 nm to 3 nm. Although this embodiment adoptsHfO₂, another High-k material, such as HfSiO, tantalum oxide (Ta₂O₅),hafnium aluminum oxide (HfAlO_(x)), or the like, may be used, or thesurface of the semiconductor substrate 11, e.g. the silicon surface, maybe simply oxidized as the gate insulating film 41. Alternatively, a highdielectric constant (High-k) insulating film may be previously formed onthe surface of the semiconductor substrate 11 and may be used as such.

The gate electrodes 43 and 63 are formed, for example, by a metalcompound layer or a metal layer. As an example, titanium nitride (TiN)is used here. As the metal layer, tungsten (W), titanium (Ti), titaniumnitride (TiN), hafnium (Hf), hafnium silicide (HfSi), ruthenium (Ru),iridium (Ir), cobalt (Co), or the like, may be selected. Although theembodiment adopts a single layer, a plurality of metal films may belayered in order to reduce resistance and adjust the threshold voltage.

Extension regions 31 and 32 are formed in the semiconductor substrate 11on the both sides of the first trench 39 in the n-type transistorforming region 12. Further, source/drain regions 35 and 36 are formed inthe semiconductor substrate 11 on the both sides of the first trench 39through the respective extension regions 31 and 32. As n-typeimpurities, phosphorus (P) or arsenic (As) are induced in the extensionregions 31 and 32 and the source/drain regions 35 and 36.

Further, in the p-type transistor forming region 13, extension regions51 and 52 are formed in the semiconductor substrate 11 on the both sidesof the second trench 59. Further, source/drain regions 55 and 56 areformed in the semiconductor substrate 11 on the both sides of the secondtrench 59 through the respective extension regions 51 and 52. As p-typeimpurities, boron (B), indium (In), or the like are induced into theextension regions 51 and 52 and the source/drain regions 55 and 56.

Silicide electrodes 37 and 38 are formed on the source/drain regions 35and 36 and silicide electrodes 57 and 58 are formed on the source/drainregions 55 and 56, thereby reducing resistance in the respectivesource/drain regions. The silicide electrodes 37, 38, 57, and 58 arerespectively formed of a silicide layer containing, for example, cobalt(Co), nickel (Ni), platinum (Pt) or their compound with a thickness ofabout 20 nm to 50 nm.

In the n-type transistor forming region 12, a first stress applying film21 having a tensile stress is formed along the side wall insulating film33 on semiconductor substrate 11, while in the p-type transistor formingregion 13, a second stress applying film 22 having a compressive stressis formed along the side wall insulating film 53 on the semiconductorsubstrate 11. In this way, it is characterized in that the first stressapplying film 21 is formed before the first trench 39 is formed and thatthe second stress applying film 22 is formed before the second trench 59is formed.

The first stress applying film 21 is formed, for example, of a siliconnitride film having a tensile stress with a film thickness of about 40nm. Although a film having a tensile stress of about 1.2 GPa is formedin the embodiment, the stress is not restricted to this value. A filmthickness is not restricted to the above film thickness of theembodiment.

Further, the second stress applying film 22 is formed, for example, of asilicon nitride film having a compressive stress with a film thicknessof about 40 nm. Although a film having a compressive stress of 1.2 GPais formed in the embodiment, the stress is not restricted to this value.A film thickness is not restricted to the above film thickness of theembodiment.

Further, a first interlayer insulating film 71 and a second interlayerinsulating film 72 are formed on the whole surface of the semiconductorsubstrate 11. These first and second interlayer insulating films 71 and72 are formed, for example, of a silicon oxide (SiO₂) film.

Contact holes 73, 74, 75, and 76 which communicate with the source/drainregions 35, 36, 55, and 56, are formed in the second interlayerinsulating film 72 and the first interlayer insulating film 71, andsource/drain electrodes 44, 45, 64, and 65 with metal such as tungsten(W) and so on embedded are formed. A semiconductor device 1 includingn-type transistor Tr1 and p-type transistor Tr2 is constructed in thisway.

Next, an embodiment (first embodiment) of a method of manufacturing asemiconductor device according to the invention will be described withreference to the cross sectional views of manufacturing processes inFIGS. 2 to 7 . Here, a method of manufacturing the semiconductor device,according to the first embodiment, will be described.

As illustrated in FIG. 2 (1), element isolating regions 14 whichelectrically separate the n-type transistor forming region 12 and thep-type transistor forming region 13 are formed in the semiconductorsubstrate 11. The above semiconductor substrate 11 adopts, for example,silicon substrate and the element isolating region 14 is formed in theSTI (Shallow Trench Isolation) structure formed, for example, of anoxide film.

Next, as illustrated in FIG. 2 (2), a protective film 80 for channelingprevention at the ion implantation is formed on the semiconductorsubstrate 11. The protective film 80 is formed, for example, of asilicon oxide film with a thickness of about 5 nm to 10 nm. Its formingmethod adopts, for example, surface oxidation. Next, after ionimplantation mask (not illustrated) which covers the p-type transistorforming region 13 is formed, the p-type impurities are induced in thesemiconductor substrate 11 of the n-type transistor forming region 12,according to the ion implantation method, to form a p-type well region15.

Thereafter, the above ion implantation mask is removed.

Next, after ion implantation mask (not illustrated) which covers then-type transistor forming region 12 is formed, the n-type impurities areinduced in the semiconductor substrate 11 of the p-type transistorforming region 13, according to the ion implantation method, to form ann-type well region 16.

Thereafter, the above ion implantation mask is removed. Further, theprotective film 80 is removed.

Whichever of the p-type well region 15 and the n-type well region 16 maybe formed first.

Next, as illustrated in FIG. 2 (3), a dummy gate insulating film 81, adummy gate forming film 82, and a hard mask layer 83 are formedsequentially on the semiconductor substrate 11.

The dummy gate insulating film 81 is formed, for example, of an oxidefilm with a thickness of about 1 nm to 3 nm. The method of forming thefilm adopts, for example, the thermal oxidation process.

The dummy gate forming film 82 is formed, for example, of a polysiliconfilm with a thickness of about 100 nm to 150 nm. Its forming methodadopts, for example, the CVD method and so on. Although the dummy gateinsulating film is removed in the post-process in the embodiment, forexample, a gate insulating film may be formed at this stage in somecases. For example, the gate insulating film may use a high dielectricconstant (High-k) insulating film of hafnium oxide (HfO₂) or the like.The dummy gate forming film 82 may adopt an amorphous silicon film.

The hard mask layer 83 uses, for example, a silicon nitride film with athickness of about 30 nm to 100 nm. The film formation method adopts,for example, the CVD method.

Then, resist (not illustrated) is patterned on the hard mask layer 83through the optical lithography technique or the electron beamlithography technique, to form a resist mask pattern (not illustrated)for forming gate electrodes of a transistor. With the resist maskpattern as a mask, the hard mask layer 83 is etched through the dryetching method or the like. After the etching, the resist mask patternis removed and with the remaining hard mask layer 83 as an etching mask,the dummy gate forming film 82 and the dummy gate insulating film 81 areetched again through the dry etching method or the like.

As the result, as illustrated in FIG. 3 (4), the dummy gates 84 and 85are formed on the semiconductor substrate 11.

It is preferable that the dry etching is performed with such a selectionratio as to etch almost none of the hard mask layer 83.

Next, as illustrated in FIG. 3 (5), in the n-type transistor formingregion 12, the extension regions 31 and 32 are formed in thesemiconductor substrate 11 of the n-type transistor forming region 12 onthe both sides of the dummy gate 84.

In the p-type transistor forming region 13, the extension regions 51 and52 are formed in the semiconductor substrate 11 of the p-type transistorforming region 13 on the both sides of the dummy gate 85.

More specifically, after forming ion implantation mask (not illustrated)which covers the p-type transistor forming region 13, according to theion implantation method, the n-type impurities are induced in thesemiconductor substrate 11 of the n-type transistor forming region 12 onthe both sides of the dummy gate 84, to form the extension regions 31and 32. In this ion implantation, for example, phosphorus (P), arsenic(As), or the like, is used as the n-type impurities. Further, forexample, a resist film is used as ion implantation mask of the n-typeimpurities. Thereafter, the above ion implantation mask is removed.

Then, after forming the ion implantation mask (not illustrated) whichcovers the n-type transistor forming region 12, the p-type impuritiesare induced in the semiconductor substrate 11 of the p-type transistorforming region 13 on the both sides of the dummy gate 85 according tothe ion implantation method, hence to form the extension regions 51 and52. In this ion implantation, for example, boron (B), indium (In), orthe like, is used as the n-type impurities. Further, for example, aresist film is used for the ion implantation mask of the p-typeimpurities.

Thereafter, the ion implantation mask is removed.

Before impurities are implanted in the respective extension regions 31,32, 51, and 52, the respective side walls of the dummy gates 84 and 85may be protected by a side wall protective film, such as a siliconnitride film, a silicon oxide film, and so on.

Next, as illustrated in FIG. 3 (6), the side wall insulating films 33and 53 are respectively formed on the respective side walls of the dummygates 84 and 85. The side wall insulating films 33 and 53 are formed,for example, in thicknesses of about 20 nm to 50 nm.

Thereafter, the source/drain regions 35 and 36 are formed in thesemiconductor substrate 11 on the both sides of the dummy gate 84through the respective extension regions 31 and 32.

Similarly, the source/drain regions 55 and 56 are formed in thesemiconductor substrate 11 on the both sides of the dummy gate 85through the respective extension regions 51 and 52.

The source/drain regions 35 and 36 are formed by ion-implanting, forexample, the n-type impurities in the semiconductor substrate 11 afterion implantation mask (not illustrated) is formed in the p-typetransistor forming region.

Next, the above ion implantation mask is removed.

Further, the source/drain regions 55 and 56 are formed byion-implanting, for example, the p-type impurities in the semiconductorsubstrate 11 after ion implantation mask (not illustrated) is formed inthe n-type transistor forming region.

Next, the above ion implantation mask is removed.

Thereafter, activation annealing is performed to activate the impuritiesimplanted in the extension regions 31, 32, 51, and 52 and thesource/drain regions 35, 36, 55, and 56. The activation annealing isperformed, for example, by rapid thermal annealing (RTA) at about 1000°C. to 1100° C.

Next, as illustrated in FIG. 4 (7), according to the salicide processtechnology, the silicide electrodes 37 and 38 are formed on thesource/drain regions 35 and 36 and the silicide electrodes 57 and 58 areformed on the source/drain regions 55 and 56, hence to reduce resistancein the respective source/drain regions. In the salicide processtechnology, a silicide layer with a thickness of about 20 nm to 50 nm isformed of cobalt (Co), nickel (Ni), platinum (Pt) or their compound.

Next, as illustrated in FIG. 4 (8), a second stress applying film(Compressive liner film) 22 having a compressive stress is formed on thewhole surface. This stress applying film 22 is formed of a siliconnitride film having a compressive stress of about 1.2 GPa with a filmthickness of 40 nm according to the plasma CVD method.

The second stress applying film 22 is formed by supplying hydrogen (H₂)gas (1000 cm³/min to 5000 cm³/min), nitrogen (N₂) gas (500 cm³/min to2500 cm³/min), argon (Ar) gas (1000 cm³/min to 5000 cm³/min), ammonia(NH₃) gas (50 cm³/min to 200 cm³/min), trimethyl silane gas (10 cm³/minto 50 cm³/min) for chemical reaction under the conditions of a substratetemperature of 400° C. to 600° C., a pressure of 0.13 kPa to 0.67 kPa,and RF power of 50 W to 500 W.

Although a film having a compressive stress of 1.2 GPa is formed in theembodiment, the stress is not restricted to this value. A film thicknessis not restricted to the above film thickness of the embodiment, either.

Thereafter, the optical lithography technique and the dry etchingtechnique are used to process the second stress applying film 22 so thatjust only on the p-type transistor forming region 13 is left.

Next, as illustrated in FIG. 4 (9), a first stress applying film(Tensile liner film) 21 having a tensile stress is formed on the wholesurface. This first stress applying film 21 is formed of a siliconnitride film having a tensile stress of about 1.2 GPa with a filmthickness of about 40 nm according to the plasma CVD method.

The first stress applying film 21 is formed by supplying nitrogen (N₂)gas (500 cm³/min to 2000 cm³/min), ammonia (NH₃) gas (500 cm³/min to1500 cm³/min), and monosilane (SiH₄) gas (50 cm³/min to 300 cm³/min) forchemical reaction under the conditions of a substrate temperature of200° C. to 400° C., a pressure of 0.67 kPa to 2.0 kPa, and RF power of50 W to 500 W. Further, after the film formation, helium (He) gas (10L/min to 20 L/min) is supplied and ultraviolet (UV) irradiation processis performed under the conditions of a temperature of 400° C. to 600°C., a pressure of 0.67 kPa to 2.0 kPa, and ultraviolet (UV) lamp powerof 1 kW to 10 kW.

Although a film having a tensile stress of 1.2 GPa is formed in theembodiment, the stress is not restricted to this value. Further, a filmthickness is not restricted to the above film thickness of theembodiment.

Thereafter, the optical lithography technique and the dry etchingtechnique are used to process the first stress applying film 21 so thatjust only on the n-type transistor forming region 12 is left. Whicheverof the first and second stress applying films 21 and 22 may be formedfirst.

Next, as illustrate in FIG. 5 (10), the first interlayer insulating film71 is formed on the whole surface of the semiconductor substrate 11.This first interlayer insulating film 71 is formed, for example, of asilicon oxide (SiO₂) film.

Next, as illustrate in FIG. 5 (11), the surface portion of the firstinterlayer insulating film 71 is removed so that the tops of therespective dummy gates 84 and 85 are exposed. In this removing process,the surface of the first interlayer insulating film 71 is polished, forexample, according to the CMP method. Then, the tops of the respectivedummy gates 84 and 85 are exposed.

Next, as illustrated in FIG. 5 (12), the dummy gates 84 and 85 (refer toFIG. 5 (11)) are removed. This removing process is performed through dryetching. Continuously, the silicon oxide film of the dummy gateinsulating film 81 is removed through wet etching using hydrofluoricacid, to form the trenches 39 and 59. Thus, the trenches 39 and 59 areformed within the side wall insulating films 33 and 53.

Next, as illustrated in FIG. 6 (13), the gate insulating film 41 isformed on the surface of the first interlayer insulating film 71including the inner surfaces of the trenches 39 and 59. This gateinsulating film 41 is formed, for example, of a hafnium oxide (HfO₂)film, a high dielectric constant (High-k) insulating film with athickness of about 2 nm to 3 nm, according to the CVD method and so on.Although the embodiment adopts HfO₂, another High-k material, such asHfSiO, tantalum oxide (Ta₂O₅), hafnium aluminum oxide (HfAlO_(x)), orthe like, may be used, or the surface of the semiconductor substrate 11,e.g. the silicon surface, may be simply oxidized as the gate insulatingfilm 41. Alternatively, a high dielectric constant (High-k) insulatingfilm may be previously formed on the surface of the semiconductorsubstrate 11 and may be used as such.

As illustrated in FIG. 6 (14), a gate electrode forming layer 42 isembedded in the trenches 39 and 59 through the gate insulating film 41.This gate electrode forming layer 42 uses, for example, a metal compoundlayer or a metal layer. Here, as one example, titanium nitride (TiN) isused. A method of forming the gate electrode forming layer 42 adopts,for example, an ALD method (Atomic Layer Deposition) or a PVD method(Physical Vapor Deposition). The embodiment adopts a titanium nitride(TiN) film having a compressive stress through the PVD method. As themetal layer, tungsten (W), titanium (Ti), titanium nitride (TiN),hafnium (Hf), hafnium silicide (HfSi), ruthenium (Ru), iridium (Ir),cobalt (Co), or the like, can be selected. Although the embodimentadopts a single layer film, a plurality of metal films may be layered inorder to reduce resistance and adjust the threshold voltage.

As illustrated in FIG. 6 (15), the surplus gate electrode forming layer42 and gate insulating film 41 on the first interlayer insulating film71 are removed such that the gate electrode forming layer 42 is embeddedin the trenches 39 and 59, hence to form the gate electrodes 43 and 63.This removing process adopts, for example, the CMP, in which the abovelayer is polished so that the surface of the first interlayer insulatingfilm 71 is exposed.

Next, as illustrated in FIG. 7 (16), the second interlayer insulatingfilm 72 is formed on the first interlayer insulating film 71. The secondinterlayer insulating film 72 is formed, for example, of a silicon oxide(SiO₂) film. After the contact holes 73, 74, 75, and 76 whichcommunicate with the source/drain regions 35, 36, 55, and 56, are boredin the second interlayer insulating film 72 and the first interlayerinsulating film 71 through the dry etching technique, metal includingtungsten (W) and so on is embedded to form the source/drain electrodes44, 45, 64, and 65, hence to complete a semiconductor device 1 includingthe n-type transistor Tr1 and the p-type transistor Tr2.

Next, the increasing effect of a stress in the above first embodimentwill be described with reference to FIGS. 8 to 10 . FIGS. 8 to 10 showthe results of stress simulation performed according to the structure ofthe above first embodiment.

FIG. 8 shows the stress in a channel of the n-type transistor in therespective processes in the conventional technique and the firstembodiment of the invention. This simulation assumes a gate length of 60nm. Also, in this simulation, an x-axis is defined as the direction fromsource to drain (direction of transistor gate length (L)), a y-axis isdefined as the direction of substrate depth from the gate electrode, anda z-axis is defined as the direction from the frontward to the backward(direction of gate width (W) of transistor), and the reference symbolsSxx, Syy, and Szz indicate the main stress components toward therespective directions. A stress in a channel indicates the value at adepth of 1 nm from the surface of the silicon substrate in the centralportion of the gate. In FIGS. 8 to 10 , “conventional technique” showsthe stress value in the state of FIG. 28 (10); “after dummy gateremoval” shows the stress value just after the removal of the dummy gateaccording to the embodiment; “after dummy gate and dummy oxide filmremoval” shows the stress value just after the removal of the dummy gateand the dummy gate insulating film (FIG. 5 (12)) according to theembodiment; and “after gate electrode formation” shows the stress valuejust after forming the gate electrodes 43 and 63 (FIG. 6 (15)), and ineach case, the values of S×x, Syy, and Szz are shown. The stress valueof plus (+) indicates a tensile stress, and the value of minus (−)indicates a compressive stress.

According to the above simulation results, it is found that the value ofSxx extremely increases just after the removal of the dummy gatecompared with the conventional technique. This shows that the stressapplied from the stressed (stress liner) film is not applied on thesemiconductor substrate (silicon substrate) effectively, due to therepulsive power from the gate electrode, in the conventional technique,but that a tensile stress is effectively applied in the x-directionafter the removal of the polysilicon dummy gate. However, it is foundthat, in the conventional technique, a compressive stress is applied asSyy, while it disappears just after the removal of the dummy gate.Further, with respect to Szz, little stress is found in the conventionaltechnique but a tensile stress is applied after the removal of the dummygate. Further, after the removal of the dummy gate insulating film, itis found that Sxx further increases by removing the dummy gateinsulating film. The trend of the stresses does not change even afterforming the gate electrodes 43 and 63.

FIG. 9 shows a change of the stress in the p-type transistor. Since thep-type transistor uses a stressed (stress liner) film having acompressive stress, contrary to the n-type transistor, thepositive/negative stress values are inverted but the trend is the sameas in the case of the n-type transistor. Namely, by removing the dummygates, the Sxx and Szz values increase but the Syy value decreases.Further, it is found that even after forming the gate electrodes 43 and63, the values still have the same trend.

As a method of estimating a change of mobility according to these stressvalues, a method of using piezoresistive coefficient is known. Accordingto the piezoresistive coefficient reported in Phys. Rev. vo. 94, pp42-49(1954) written by C. S. Smith, each mobility enhancement factor in then-type and the p-type transistors can be described as follows.

-   -   n-type: (μxx/μ0)=1+0.316Sxx−0.534Syy+0.176Szz    -   p-type: (μxx/μ0)=1−0.718Sxx+0.011Syy+0.663Szz

The plot of each mobility enhancement factor in the respective statesaccording to the above formulas is shown in FIG. 10 . The Sxx, Syy, andSzz values used for the calculation are those as shown in FIGS. 8 and 9. The mobility enhancement factor is the relative value when themobility in the state of no stress applied is defined as 1.

As illustrated in FIG. 10 , it is found that the mobility is extremelyimproved by removing the dummy gates 84 and 85. The mobility is furtherimproved by removing the dummy gate insulating film 81. Owing to this,it is found that the removal of the dummy gate insulating film 81 ispreferable to the previous formation of High-k insulating film under thedummy gates 84 and 85. The mobility enhancement factor after forming theembedded gate decreases a little in the p-type transistor Tr2 becausethe TiN of the gate electrode forming layer 42 has a compressive stress.Compared with the conventional technique, however, it is found that thetransistor according to the first embodiment improves the mobilityenhancement factor in both the n-type and the p-type much more than theconventional technique.

Another embodiment (second embodiment) of a semiconductor deviceaccording to the invention, will be described with reference to theschematic cross sectional structural view in FIG. 11 .

As illustrated in FIG. 11 , element isolating regions 14 whichelectrically separate an n-type transistor forming region 12 and ap-type transistor forming region 13, are formed on a semiconductorsubstrate 11. For example, silicon substrate is used for thesemiconductor substrate 11 and the element isolating region 14 is formedin the STI (Shallow Trench Isolation) structure including, for example,an oxide film.

A p-type well region 15 with the p-type impurities induced is formed inthe semiconductor substrate 11 of the n-type transistor forming region12, and an n-type well region 16 with the n-type impurities induced isformed in the semiconductor substrate 11 of the p-type transistorforming region 13.

On the semiconductor substrate 11, a side wall insulating film 33 havinga first trench 39 which is formed by removing the first dummy gate (notillustrated), is formed in the n-type transistor forming region 12 and aside wall insulating film 53 having a second trench 59 which is formedby removing the second dummy gate (not illustrated), is formed in thep-type transistor forming region 13. The side wall insulating films 33and 53 are formed, for example, in thicknesses of about 20 nm to 50 nm.

A gate electrode 43 is formed within the first trench 39 through thegate insulating film 41 and a gate electrode 63 is formed within thesecond trench 59 through the gate insulating film 41.

The gate insulating film 41 is formed, for example, of a hafnium oxide(HfO₂) film, a high dielectric constant (High-k) insulating film, with athickness of about 2 nm to 3 nm. Although this embodiment adopts HfO₂,another High-k material, such as HfSiO, tantalum oxide (Ta₂O₅), hafniumaluminum oxide (HfAlO_(x)), or the like, may be used, or the surface ofthe semiconductor substrate 11, e.g. the silicon surface may be simplyoxidized, or the high dielectric constant film previously formed on thesurface of the semiconductor substrate 11 may be used as the gateinsulating film 41.

The gate electrodes 43 and 63 adopt, for example, a metal compound layeror a metal layer. Here, as one example, titanium nitride (TiN) is used.As the metal layer, tungsten (W), titanium (Ti), titanium nitride (TiN),hafnium (Hf), hafnium silicide (HfSi), ruthenium (Ru), iridium (Ir),cobalt (Co), or the like, can be selected. Although the embodimentadopts a single layer film, a plurality of metal films may be layered inorder to reduce resistance and adjust the threshold voltage.

In the n-type transistor forming region 12, extension regions 31 and 32are formed in the semiconductor substrate 11 on the both sides of thefirst trench 39. Further, source/drain regions 35 and 36 are formed inthe semiconductor substrate 11 on the both sides of the first trench 39through the respective extension regions 31 and 32. As the n-typeimpurities, phosphorus (P) or arsenic (As) are induced in the extensionregions 31 and 32 and the source/drain regions 35 and 36.

Further, in the p-type transistor forming region 13, extension regions51 and 52 are formed in the semiconductor substrate 11 on the both sidesof the second trench 59. Further, source/drain regions 55 and 56 areformed in the semiconductor substrate 11 on the both sides of the secondtrench 59 through the respective extension regions 51 and 52. As thep-type impurities, boron (B), indium (In), or the like are induced inthe extension regions 51 and 52 and the source/drain regions 55 and 56.

Silicide electrodes 37 and 38 are formed on the source/drain regions 35and 36 and silicide electrodes 57 and 58 are formed on the source/drainregions 55 and 56, hence to reduce resistance in the respectivesource/drain regions. The silicide electrodes 37, 38, 57, and 58 arerespectively formed of a silicide layer containing, for example, cobalt(Co), nickel (Ni), platinum (Pt) or their compound with a thickness ofabout 20 nm to 50 nm.

In the n-type transistor forming region 12, a first stress applying film21 having a tensile stress is formed along the side wall insulating film33 on the semiconductor substrate 11, while in the p-type transistorforming region 13, a second stress applying film 22 having a compressivestress is formed along the side wall insulating film 53 on thesemiconductor substrate 11. In this way, it is characterized in that thefirst stress applying film 21 is formed before the first trench 39 isformed and that the second stress applying film 22 is formed before thesecond trench 59 is formed.

The first stress applying film 21 is formed, for example, of a siliconnitride film having a tensile stress with a film thickness of about 40nm. Although this embodiment forms a film having a tensile stress ofabout 1.2 GPa, the stress is not restricted to this value. A filmthickness is not restricted to the above film thickness of theembodiment. Further, the second stress applying Film 22 is formed, forexample, of a silicon nitride film having a compressive stress with afilm thickness of about 40 nm. Although a film having a compressivestress of 1.2 GPa is formed in the embodiment, the stress is norestricted to this value. A film thickness is not restricted to theabove film thickness of the embodiment.

Further, a third stress applying film 23 having a tensile stress isformed on the first stress applying film 21 and a fourth stress applyingfilm 24 having a compressive stress is formed on the second stressapplying film 22.

The third stress applying film 23 is formed, for example, of a siliconnitride film having a tensile stress with a film thickness of about 40nm. Although a film having a tensile stress of 1.2 GPa is formed in theembodiment, the stress is not restricted to this value. A film thicknessis not restricted to the above film thickness of the embodiment.

The fourth stress applying film 24 is formed, for example, of a siliconnitride film having a compressive stress with a film thickness of about40 nm. Although a film having a compressive stress of 1.2 GPa is formedin the embodiment, the stress is not restricted to this value. A filmthickness is not restricted to the film thickness of the embodiment.

Further, a first interlayer insulating film 71 and a second interlayerinsulating film 72 are formed on the whole surface of the semiconductorsubstrate 11. The first and second interlayer insulating films 71 and 72are formed, for example, of a silicon oxide (SiO₂) film.

Contact holes 73, 74, 75, and 76 which communicate with the source/drainregions 35, 36, 55, and 56, are formed in the second interlayerinsulating film 72 and the first interlayer insulating film 71, andsource/drain electrodes 44, 45, 64, and 65 with metal such as tungsten(W) and so on embedded are formed. A semiconductor device 2 includingn-type transistor Tr1 and p-type transistor Tr2 is constructed in thisway.

Next, another embodiment (second embodiment) of a method ofmanufacturing a semiconductor device according to the invention, will bedescribed with reference to the cross sectional views of manufacturingprocesses in FIGS. 12 to 13 . Here, a method of manufacturing thesemiconductor device, according to the second embodiment, will bedescribed.

The manufacturing method according to the second embodiment will beperformed as follows.

First, by performing the processes having been described according toFIGS. 2 (1) to 6(15), the surplus gate electrode forming layer 42 andgate insulating film 41 on the first interlayer insulating film 71 areremoved such that the gate electrode forming layer 42 is embedded in thetrenches 39 and 59, hence to form the gate electrodes 43 and 63, asillustrated in FIG. 12 (1). This removing process adopts, for example,the CMP, in which the above layer is polished so that the surface of thefirst interlayer insulating film 71 is exposed.

Next, as illustrated in FIG. 12 (2), the first interlayer insulatingfilm 71 (refer to FIG. 12 (1)) is removed according to the dry etchingmethod.

Next, as illustrated in FIG. 12 (3), the fourth stress applying film 24having a compressive stress is formed only on the p-type transistorforming region 13. For example, a silicon nitride film (Compressiveliner film) having a compressive stress with a film thickness of about40 nm is formed on the whole surface, according to the plasma CVD methodand it is left just only on the p-type transistor forming region 13,according to the optical lithography technique and the dry etchingtechnique, hence to form the fourth stress applying film 24. Although,in the embodiment, it is formed with a thickness of 40 nm of a filmhaving the same compressive stress of 1.2 GPa as the previously formedsecond stress applying film 22 having a compressive stress, it is notrestricted to this stress and film thickness.

Next, as illustrated in FIG. 13 (4), the third stress applying film 23having a tensile stress is formed only on the n-type transistor formingregion 12. For example, a silicon nitride film (Tensile liner film)having a tensile stress with a film thickness of 40 nm is formed on thewhole surface, according to the plasma CVD method and it is left justonly on the n-type transistor forming region 12, according to theoptical lithography technique and the dry etching technique, hence toform the third stress applying film 23. Although, in the embodiment, itis formed with a film thickness of 40 nm of a film having the sametensile stress of 1.2 GPa as the previously formed first stress applyingfilm 21 having a tensile stress, it is not restricted to this stress andfilm thickness.

Next, as illustrated in FIG. 13 (5), an interlayer insulating film 77 isformed. This interlayer insulating film 77 is formed, for example, ofsilicon oxide (SiO₂).

Next, as illustrated in FIG. 13 (6), contact holes 73, 74, 75, and 76which communicate with the source/drain regions 35, 36, 55, and 56, arebored in the interlayer insulating film 77 through the dry etchingtechnique, then, metal including tungsten (W) and so on is embedded toform the source/drain electrodes 44, 45, 64, and 65, hence to complete asemiconductor device 2 including the n-type transistor Tr1 and thep-type transistor Tr2.

Next, the increasing effect of a stress in the above second embodimentwill be described with reference to FIGS. 14 to 16 . FIG. 14 shows thestress simulation values in the n-type transistor according to theconventional technique, the first embodiment, and the second embodiment.

As illustrated in FIG. 14 , it is found that, in the second embodiment,the compressive stress in the depth direction is recovered to a degreebecause the third stress applying film having a tensile stress is formedon the gate electrode manufactured through the embedding process, whilein the first embodiment, the compressive stress (Syy) in the depthdirection is decreased because the top of the first stress applying filmhaving a tensile stress is removed through the CMP and the dummy gate isremoved by etching. According to the formula of mobility enhancementfactor shown in the first embodiment, it is found that, in the n-typetransistor, the mobility is improved more as the compressive stress,that is, the minus value of the stress (Syy) in the depth direction,becomes larger. Therefore, the third stress applying film having atensile stress is effective in improving the mobility.

As illustrated in FIG. 15 , by forming the fourth stress applying filmhaving a compressive stress even in the p-type transistor, the Syy valuebecomes larger. In the case of the p-type transistor, however, theeffect is restrictive because the coefficient of the Syy is small in theformula for mobility enhancement factor.

As illustrated in FIG. 16 indicating the improving ratio of mobilitycalculated based on the respective stress values, the second embodimentcan achieve the further improvement of mobility both in the n-type andp-type transistors than the first embodiment.

Next, another embodiment (third embodiment) of a semiconductor deviceaccording to the invention, will be described with reference to theschematic cross sectional structural view in FIG. 17 .

As illustrated in FIG. 17 , a semiconductor device 3 according to thethird embodiment is constituted in that a third stress applying film 23having a tensile stress is formed on the first and second stressapplying films 21 and 22 so as to cover the respective gate electrodes43 and 63, on the basis of the semiconductor device 1 in the firstembodiment having been described with FIG. 1 . The other components arethe same as those of the semiconductor device 1 in the first embodiment.In the drawing, the illustration of the source/drain electrodes isomitted.

Next, another embodiment (third embodiment) with respect to a method ofmanufacturing a semiconductor device according to the invention, will bedescribed. Here, a method of manufacturing the semiconductor device 3will be described.

According to the manufacturing method in the third embodiment, theprocesses up to FIG. 12 (2) are performed and thereafter, the thirdstress applying film 23 having a tensile stress is formed on the wholesurface, as illustrated in FIG. 17 . Thereafter, the processes afterFIG. 12 (5) will be performed.

In the semiconductor device 3 according to the third embodiment, thefirst stress applying film 21 having a tensile stress and the secondstress applying film 22 having a compressive stress in the first layerare the same as those of the first and the second embodiments but in thesecond layer, there exists only the third stress applying film 23 havinga tensile stress. According to this, it is not necessary to form astress applying film in the second layer separately in the n-type andthe p-type like in the second embodiment, thereby reducing the processand improving the yield. Although, in the third embodiment, the thirdstress applying film 23 having a tensile stress adopts a silicon nitridefilm having a tensile stress of 1.2 GPa with a thickness of 40 nm, thefilm thickness and the internal stress are not restricted to the above.In the embodiment, since the p-type transistor has the third stressapplying film 23 having a tensile stress, its property changes in anundesirable direction but the undesirable power is not so large.

Next, another embodiment (fourth embodiment) of a semiconductor deviceaccording to the invention, will be described with reference to theschematic cross sectional view in FIG. 18 .

As illustrated in FIG. 18 , in the semiconductor device 4 according tothe fourth embodiment, the source/drain regions 55 and 56 of the p-typetransistor are formed by stress applying sources, on the basis of thesemiconductor device 3 according to the third embodiment having beendescribed with FIG. 17 . This stress applying source is formed, forexample, of a silicon germanium (SiGe) layer. The other components arethe same as those of the semiconductor device 3.

Next, another embodiment (fourth embodiment) of a method ofmanufacturing a semiconductor device according to the invention, will bedescribed. Here, a method of manufacturing the semiconductor device 4will be described.

The manufacturing method according to the fourth embodiment will beperformed as follows.

First, the processes having been described according to FIGS. 2 (1) to3(6) are performed. At that time, the source/drain regions 55 and 56 ofthe p-type transistor are formed by the stress applying sources. Thestress applying source is formed, for example, through germaniumimplantation. Alternatively, the forming regions of the source/drain areremoved through etching, to form trenches, and a silicon germanium(SiGe) layer is epitaxial-grown selectively in the trench portions. Inthis case, the other portion is covered with an insulating film toprotect against the epitaxial growth. The insulating film is removedafter the epitaxial growth. In the fourth embodiment, a silicongermanium (SiGe) layer formed through epitaxial growth is used as thestress applying source having a compressive stress. The germanium (Ge)concentration is, for example, 18% but the germanium concentration isnot restricted to this. Although the embodiment adopts SiGe, it is notrestricted to SiGe as far as it can apply a compressive stress to achannel region.

Further, a method of applying a compressive stress on a p-typetransistor by using SiGe for the source/drain regions is described, forexample, in JP-A-2006-186240, “IEDM2003 Technical Digest” written by T.Ghani et al., and “A 90 nm High Volume Manufacturing Logic TechnologyFeaturing Novel 45 nm Gate Length Strained Silicon CMOS Transistors”(p.987 (US), 2003).

Then, the processes having been described according to FIGS. 4 (7) to6(15) are performed. After the process shown in FIG. 12 (2), the thirdstress applying film 23 having a tensile stress is formed on the wholesurface, as illustrated in FIG. 17 . The processes after the processshown in FIG. 12 (5) are performed.

The effects of the third and fourth embodiments will be described usingthe simulation results shown in FIGS. 19 and 20 . With respect to then-type transistor, the results are the same as in the case of the secondembodiment 2 and their description is omitted. FIG. 19 shows the stresssimulation results in the p-type transistor according to theconventional technique, the first embodiment, the third embodiment, andthe fourth embodiment. Further, FIG. 20 shows a comparison of mobilityenhancement factor in the respective cases.

As illustrated in FIG. 19 , the third stress applying film 23 in thesecond layer formed in the p-type transistor is a film having a tensilestress in the third embodiment, and according to this effect, the valueof compressive stress of Syy becomes larger than that of the firstembodiment. According to the formula for mobility enhancement factor,mobility gets smaller in the p-type transistor as the compressive stressof Syy gets larger. In the fourth embodiment, since the compressivestress source is formed in the source/drain regions, the compressivestress (Sxx) in the channel direction increases largely.

As illustrated in FIG. 20 , in the third embodiment, since thecompressive stress (Syy) in the depth direction increases, mobilityenhancement factor gets smaller than that in the case of the firstembodiment, but the mobility is more improved compared with theconventional technique. Since the compressive stress (Sxx) in thechannel direction is much improved in the fourth embodiment, a largermobility enhancement factor can be achieved. In the third and the fourthembodiments, a stress applying film in the second layer is formed of asilicon nitride film having a tensile stress in order not to deterioratethe mobility enhancement in the n-type transistor; when the mobilityenhancement in the p-type transistor is important, however, the stressapplying film in the second layer may be formed of a compressive linerfilm having a compressive stress.

Another embodiment (fifth embodiment) of a semiconductor deviceaccording to the invention, will be described according to the schematiccross sectional view in FIG. 21 .

As illustrated in FIG. 21 , a semiconductor device 5 according to thefifth embodiment is constituted in that a stress applying film is notformed in the p-type transistor, on the basis of the semiconductordevice 4 according to the fourth embodiment having been described inFIG. 18 . Namely, as the stress applying film, there are only the firststress applying film 21 and the third stress applying film 23 eachhaving a tensile stress in the n-type transistor. The other componentsare the same as those of the semiconductor device 4.

Next, another embodiment (fifth embodiment) of a method of manufacturinga semiconductor device according to the invention, will be described.Here, the method of manufacturing the semiconductor device 5 will bedescribed.

According to the manufacturing method of the fifth embodiment, a secondstress applying film having a compressive stress is not formed but athird stress applying film 23 having a tensile stress is formed on thefirst stress applying film 21 having a tensile stress, and the thirdstress applying film 23 in the p-type transistor region is removed, onthe basis of the manufacturing method of the fourth embodiment. Theother processes are the same as those of the manufacturing method of thefourth embodiment.

In the fifth embodiment, the process can be further shortened than inthe fourth embodiment. Further, stress applying films having stresses(the first stress applying film 21 and the third stress applying film 23having tensile stresses) are formed only on the n-type transistor.While, in the p-type transistor, the source/drain regions 55 and 56 areformed of SiGe layer through epitaxial growth so that the source/drainregions 55 and 56 may be stress applying sources, similarly to thefourth embodiment. According to this, since the channel region of thep-type transistor receives a compression power from the SiGe layer inthe channel direction, mobility can be enhanced and ability oftransistor can be improved without forming a stress applying film havinga compressive stress. Although the fifth embodiment adopts SiGe, it isnot restricted to SiGe as far as it can apply a compressive stress on achannel region.

Another embodiment (sixth embodiment) of a semiconductor deviceaccording to the invention, will be described with reference to theschematic cross sectional structural view in FIG. 22 .

As illustrated in FIG. 22 , the semiconductor device 6 of the sixthembodiment is constituted in that the third stress applying film 23having a tensile stress is formed on the whole surface, on the basis ofthe semiconductor device 5 of the fifth embodiment. The other componentsare the same as those of the semiconductor device 5 of the fifthembodiment.

Next, another embodiment (sixth embodiment) of a method of manufacturinga semiconductor device of the invention, will be described. Here, amanufacturing method of the semiconductor device 6 will be described.

According to the manufacturing method of the sixth embodiment, the thirdstress applying film 23 having a tensile stress is formed on the wholesurface and is left there without removing the third stress applyingfilm 23 in the p-type transistor region, on the basis of themanufacturing method of the fifth embodiment. The other manufacturingprocesses are the same as those of the manufacturing method of the fifthembodiment.

In the semiconductor device 6 in the sixth embodiment, although thethird stress applying film having a tensile stress works in a directionof deteriorating the transistor ability in the p-type transistor, thethird stress applying film is formed after the gate electrode is formedand therefore, its effect is not so large, similarly to the thirdembodiment. Further, although the first stress applying film and thethird stress applying film having tensile stresses are formed in thefirst layer and the second layer on the n-type transistor, the thirdstress applying film in the second layer may be omitted for the purposeof shortening the process.

The effects of the fifth and the sixth embodiments will be described byusing the simulation results shown in FIG. 23 and FIG. 24 . The n-typetransistor is the same as in the case of the second embodiment and itsdescription is omitted. FIG. 23 shows the stress simulation results inthe p-type transistor according to the conventional technique, the firstembodiment, the fifth embodiment, and the sixth embodiment. FIG. 24shows a comparison of mobility enhancement factor in the respectivecases.

As illustrated in FIG. 23 , according to the fifth embodiment, since thecompressive stress sources including SiGe are used in the source/drainregions instead of a stress applying film having a compressive stress inthe p-type transistor, they take the almost same values as those of thefirst embodiment. Since the third stress applying film having a tensilestress is formed in the sixth embodiment, the compressive stress of Sxxdecreases to a degree and the compressive stress of Syy largelyincreases.

As illustrated in FIG. 24 , in the fifth embodiment, since thecompressive stress (Sxx) in a horizontal direction increases, mobilityenhancement factor gets larger compared with that of the firstembodiment. On the other hand, in the sixth embodiment, since thecompressive stress of Syy increases due to the effect of the thirdstress applying film 23 having a tensile stress, mobility enhancementfactor is substantially the same as the enhancement ratio of the firstembodiment. The both cases can achieve larger mobility enhancementfactor compared with the conventional technique. In the fifth and sixthembodiments, the source/drain regions 55 and 56 in the p-type transistorare formed of SiGe layer, hence to apply a compressive stress in achannel, while also in the n-type transistor, the source/drain regions35 and 36 in the n-type transistor may be formed of layer having atensile stress, such as SiC and so on, thereby making a structure ofhaving stress applying sources in the source/drain regions 35 and 36similarly.

Another embodiment (seventh embodiment) of a semiconductor deviceaccording to the invention, will be described with reference to theschematic cross sectional structural view in FIG. 25 .

As illustrated in FIG. 25 , the semiconductor device 7 according to theseventh embodiment is constituted in that the source/drain regions 55and 56 in the p-type transistor are formed by stress applying sources,on the basis of the semiconductor device 2 of the second embodimenthaving been described according to FIG. 11 . The stress applying sourceis formed, for example, of a silicon germanium (SiGe) layer. The othercomponents are the same as those of the semiconductor device 2.

Next, another embodiment (seventh embodiment) of a method ofmanufacturing a semiconductor device according to the invention, will bedescribed. Here, a manufacturing method of the semiconductor device 7will be described.

According to the manufacturing method of the seventh embodiment, thesource/drain regions 55 and 56 in the p-type transistor are formed ofstress applying sources, on the basis of the manufacturing method of thesecond embodiment. The stress applying source is formed, for example,through germanium implantation. Alternatively, the source/drain formingregions are removed through etching to form trenches, and a silicongermanium (SiGe) layer is selectively epitaxial-grown in the trenchportions. In this case, the other region is covered with an insulatingfilm so as to protect against the epitaxial growth. This insulating filmis removed after the epitaxial growth. In the fourth embodiment, asilicon germanium (SiGe) layer epitaxially grown is used as a stressapplying source having a compressive stress. The germanium (Ge)concentration is, for example, 18% but the germanium concentration isnot restricted to this. Although the embodiment adopts SiGe, it is notrestricted to SiGe as far as it can apply a compressive stress to achannel region.

In the semiconductor device 7 of the seventh embodiment, a SiGe layermanufactured through the epitaxial growth is formed in the source/drainregions 55 and 56 in the p-type transistor, similarly to the third andthe fourth embodiments, and further the second stress applying film andthe fourth stress applying film having compressive stresses are formed,similarly to the second embodiment. Therefore, compressive stress fromthe SiGe layer and compressive stresses from the second and third stressapplying films are applied on the channel regions under the gateelectrode in the p-type transistor, thereby applying a large stress on achannel region. Further, the same structure as that of the secondembodiment is adopted in the n-type transistor, thereby enhancingmobility extremely both in the n-type and p-type transistors.

Further, also in the seventh embodiment, a layer having a tensilestress, such as SiC and so on, is formed in the source/drain regions inthe n-type transistor, thereby making a structure of having a stressapplying source in the source/drain regions.

1-16. (canceled)
 17. A semiconductor device comprising: a side wallinsulating film formed on a semiconductor substrate with a trench; agate insulating film and a gate electrode formed on the semiconductorsubstrate within the trench; a first stress applying film formed afterthe trench is form and located along the side wall insulating film overthe semiconductor substrate; and source/drain regions formed in thesemiconductor substrate on opposite sides of the gate electrode.
 18. Thesemiconductor device according to claim 17, wherein the semiconductordevice is an n-type transistor and the first stress applying film has atensile stress.
 19. The semiconductor device according to claim 17,wherein the semiconductor device is an p-type transistor and the firststress applying film has a compressive stress.
 20. The semiconductordevice according to claim 17, further comprising: a second stressapplying film on the first stress applying film.
 21. The semiconductordevice according to claim 17, wherein the first stress applying film isformed of silicon nitride.
 22. The semiconductor device according toclaim 17, further comprising: silicide regions at surfaces of thesource/drain regions at the opposite sides of the gate electrode, thesilicide regions being between the source/drain regions and the firststress applying film and in contact with the first stress applying film.23. The semiconductor device according to claim 21, wherein the silicideregions do not extend under the side wall insulating film.
 24. Thesemiconductor device according to claim 17, further comprising a lightlydoped drain region in the substrate.